This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Increasingly, mobile radio handsets incorporate one or multiple radios that operate over different protocols and different frequency bands. This is true over multiple cellular band as with tri and quad-band mobile devices that operate in several cellular systems such as GSM (global system for mobile communications, or 3G), UTRAN (universal mobile telecommunications system terrestrial radio access network, or 3.5G), WCDMA (wideband code division multiple access), and OFDMA (orthogonal frequency division multiple access), to name but a few examples. Additionally, many handsets come equipped with secondary radios such a global positioning system GPS, Bluetooth, wireless local area network WLAN, and/or traditional FM radio that operate alongside the cellular band radios.
Simultaneous with this desire for communication over diverse frequency bands is the continued preference of ever smaller handsets. This creates several technological challenges, not least of which is design and placement of antennas for such varied bands in the small and crowded handset in a manner that generally assures reliable signal transmission and reception without excessive interference with or from other electronics within that same handset housing.
This is a challenging environment for the antenna designer. There are quite strict requirements for several operating bands, and the small antenna volumes available within the handset impose conflicting constraints. Especially cellular bands are very difficult to cover with a single resonance and so require either multiple antennas or tunable antennas. This readily leads to complicated matching topologies, adding to the designer's burden of simultations and difficulty in finding an operable solution.